1. Field of the Invention
This invention relates to a water drain device of a revolving electric machine such as an electric motor and a generator.
2. Related Art Statement
In general, in a revolving electric machine such as an electric motor or generator, to prevent water from accumulating in the machine due to moisture condensation and the like, a water drain hole is opened at the bottom of the housing.
Now, for example, with a starter motor and the like mounted on a vehicle such as a motor vehicle, a motor cycle and the like, there are situations cases where the bottom portion of a housing of a revolving electric machine is splashed with water. In such situations, the water reversely intrudes into the housing through a water drain hole, inviting such problems as electric insulation deterioration, corrosion of a conductive portion, lubrication becoming poor in a movable section, and so forth.
Conventionally in the revolving electric machine of the type described, as a means for preventing the water from intruding through the water drain hole opened in the bottom portion of the housing, there has been used a water drain device, to which a tube such as a rubber tube and the like is connected.
On the other hand, in the case of a motor provided with an oil seal, a water drain device is adopted intended to function when immersed in water and an oil drain construction intended to oil at the time of the wear the oil seal and like as described in Japanese Utility Model Unexamined Publication No. 62-198849 for example.
However, in the case of the motor with an oil seal having the conventional oil drain construction and water drain construction, the respective constructions are provided independently of each other, whereby rubber parts and resinous parts are used in the respective constructions, thereby presenting the disadvantages that costs rise and the number of man-hours for assembling is increased.
When only a tube such as a rubber tube is mounted to the water drain hole, the splashed water intrusion preventive effect is low. Therefore, as described in Japanese Utility Model Examined Publications Nos. 62-2905 and 62-2906, such a technique has been proposed that a plurality of baffle plates are projected in the intermediate portion of the tube with a water way being left, whereby a labyrinth is formed, so that the splashed water can be effectively prevented from intruding.
However, when the baffle plates are formed in the intermediate portion of the rubber tube, the baffle plates are formed by a so-called forced extrusion method by utilizing the elasticity of a rubber material at the time of resin molding of the rubber tube, so that allowance of overlap between the baffle plates cannot be set at a large value.
As a result, the splashed water intrusion preventive effect by the baffle plates is limited.